The processing of poultry such as chickens and turkeys has become highly automated. Birds generally are suspended by their legs from shackles attached to and conveyed by an overhead conveyor system. The conveyor system conveys the shackles and the birds along a processing path for de-feathering, evisceration, cut-up, and other processing. It is highly desirable to perform as many of the cut-up and processing operations as possible while the birds are suspended from their shackles to minimize human handling and ensure greater uniformity in the cutting and processing of the birds. Accordingly, the birds are conveyed through various processing stations while they move in series along the processing path suspended from their shackles. For example, the birds can be de-feathered, decapitated, opened, eviscerated, and cut into individual parts while being advanced progressively along the processing path suspended from their shackles, all without having to remove the birds from the shackles. As a result, the labor required for processing poultry can be significantly reduced while uniformity and adjustability in the sectioning of the poultry carcasses into various poultry parts is more predictable.
One processing operation that typically is performed along the processing path is the separation of the thigh from the drumstick of a poultry leg at the knee joint. Numerous automated machines have been developed in the past for performing this processing operation. Some of these machines include an overhead conveyor with shackles from which poultry legs are suspended and moved along a processing path. The suspended poultry legs are conveyed through a cutting station that may include a large rotating disc with peripheral notches. The disc rotates synchronously with the overhead conveyor, which conveys the parts around the arc of the disc. The suspended poultry legs encounter the notches in the disc, which support the leg, position the knee joint, and clamp the thigh. As the legs and thighs are moved around by the rotating disc, they engage a cutting device such as a rotating blade that cuts the drumstick from the thigh at the knee joint to produce separate parts.
While prior art techniques and machines for separating poultry thighs from drumsticks at the knee joint have been somewhat successful, they nevertheless have been plagued with shortcomings inherent in their respective designs. For example, machines that capture poultry parts in peripheral notches to stabilize them for cutting can be sensitive to the size of the parts being processed. This can require frequent adjusting, especially when the line is switched from larger birds to smaller birds or vice versa. In addition, there is a tendency for the cutting blade not to be precisely aligned with the knee joint when the cut is made. This results in not infrequent cuts through bones and/or cartilage rather than between the ends of the bones. This is not only unsightly, but can result in bone shards and splinters becoming lodged in the meat of the drumstick or thigh, thus reducing its value or requiring expensive manual clean-up. As a result of these and other shortcomings, traditional machines have production yields, i.e. the percentage of parts cut apart cleanly and not needing manual processing, of around 80 to 85%.
A need exists for an automated apparatus and method for separating poultry legs into their constituent thighs and drumsticks that successfully addresses the problems and shortcomings of the prior art. Such an apparatus and method should be highly adaptable to poultry legs of different sizes without manual adjustment, should consistently produce cuts between the bones of the knee joint and not through bone or cartilage, and should operate with a production yields as high as 90 to 95%. It is to the provision of such an apparatus and method that the present invention is primarily directed.